The influence of different doses of γ-radiation on the hydrolytic stability of modified urea-formaldehyde (UF) resins

Zbog emisije formaldehida (CH2 O) iz drvenih proizvoda, gde se urea- formaldehidne (UF) smole, između ostalog, koriste za impregnaciju drvenih panela koje se koriste u unutrašnjosti stambenih i drugih objekata poželjno je da procenat slobodnog formaldehida (CH2 O) u samoj smoli bude što manji, jer je poznato da formaldehid ima štetno dejstvo na čoveka, odnosno ceo živi svet. Pare formaldehida jako nadražuju disajne puteve. Koncentracije od 10-20 ppm otežavaju disanje, a koncentracije od 650 ppm mogu uzrokovati i smrt za samo nekoliko minuta. Često udisanje para niskih koncentracija mogu uzrokovati hronična oboljenja disajnih puteva. Simptomi i granice su individualni i javljaju se u širokim granicama izloženosti. Pojedine osobe mogu da osete simptome, kao što su iritacija očiju, grla, umor, glavobolja i mučnina, usled izloženosti i niskoj koncentaciji formaldehida (0.1 do 1 ppm). Osim slobodnog formaldehida, u samoj smoli, koji se spontano emituje, zbog niske otpornosti na vlagu, može doći do hidrolize UF smole što podrazumeva raskidanje samih veza u smoli (metilenetarskih) i dodatne emisije formaldehida u okolinu [1,2]. U ovom radu je ispitivana hidrolitička stabilnost modifikovanih UF smola sa “hvatačima” formaldehida, TiO2 sa različitim sadržajem (3,75 g i 7,25 g) u UF smoli i kombinacijom TiO2 i drvnog brašna (TiO2 /DB) u ekvimolarnim količinama. Tri modifikovane UF smole s odnosom formaldehida i uree (F/U) 0.8 s modifikovanim punilima su sintetizovani istim postupkom [3]. Hidrolitička stabilnost ispitivanih modifikovanih UF smola je određivana merenjem koncentracije oslobođenog formaldehida [4] iz modifikovane UF smole nakon kisele hidrolize. Zračenje sintetisanih modifikovanih smola je vršeno u vazdušnoj atmosferi u Co-60 radijacionoj jedinici na Institutu za nuklearne nauke, Vinča, Srbija. Uzorci smola su zračeni γ–zračenjem na sobnoj temperaturi i ukupnom apsorbovanom dozom od 50 kGy i 100 kGy [5]. Pre zračenja najmanji procenat slobodnog formaldehida (0.06%) imaju uzorci koji su modifikovani TiO2 . Usled γ-zračenja dolazi do degradacije makromolekula što uzrokuje povećanje slobodnog formaldehida u zračenim uzorcima u odnosu na nezračene. Povećanje doze zračenja sa 50 kGy na 100 kGy dovodi do smanjenja količine slobodnog formaldehida u umreženoj UF smoli. Najmanji procenat slobodnog formaldehida nakon zračenja sa ukupnom apsorbovanom dozom od 100 kGy nalazi se u UF smoli koja sadrži 100% TiO2 u količini od 0.12%. S druge strane i drvno brašno koje sadrži celulozu i hemicelulozu ima veliki broj hidroksilnih grupa, takođe reaguje sa slobodnim formaldehidom iz UF smole. γ-zračenjem je smanjen procenat oslobođenog formaldehida u svim ispitivanim modifikovanim UF smolama, posebno kod uzoraka smole sa TiO2 u količini od 100% u izosu od 0.25%. To se objašnjava činjenicom da kisela hidroliza nakon zračenja dovodi do dodatnog umrežavanja u svim uzorcima, što rezultuje „hvatanjem“ formaldehida u toku samog procesa hidrolize. Uzorci ispitivane kompozitne smole sa TiO2 /DB pokazuju lošiju hidrolitičku stabilnot zbog povećane interakcije između hidroksilnih i karbonilnih grupa u drvnom brašnu i hidroksilnih grupa sa površine TiO2 , zbog čega dolazi do smanjene interakcije hibridnog punila sa polimernom matricom odnosno smanjuje se procenat slobodnih grupa koje bi inače reagovale sa formaldehidom i smanjile njegovu emisiju iz smole.8th Symposium Chemistry and Environmental Protection : May 30 - June 1, Kruševac, 2018

The possibility of in vitro multi-enzymatic method application for the assessment of the influence of thermal treatments on organic matter digestibility of feed for ruminants

In vitro multi-enzymatic method is a two-step procedure that uses exogenous enzymes for incubation of feed that aim to imitate digestive processes in the animal. It is used for determination of organic matter digestibility (OMD) of various feedstuffs and complete mixtures used in ruminant nutrition. The aim of the present work was to determine whether this in vitro multi-enzymatic method can be applied for the assessment of the influence of thermal treatments on OMD of feed for ruminants. Samples of corn and complete mixture for cows (based on corn) were subjected to pelleting, steam flaking, micronization and extrusion. Statistical analysis of the results did not show significant increase of corn and complete mixture OMD after various thermal treatments compared to untreated samples, which can be explained by high digestibility of corn itself (exceeds 90%). Based on obtained results it can be concluded that applied in vitro method is not suitable for the assessment of the influence of thermal treatments on OMD of corn and corn based mixture, while future research should be broadened to analysis of samples with lower OMD, such as sorghum, oats and barley

Lipid anti-lipid antibody responses correlate with disease activity in systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder characterized by broad clinical manifestations including cardiovascular and renal complications with periodic disease flares and significant morbidity and mortality. One of the main contributing factors to the pathology of SLE is the accumulation and impaired clearance of immune complexes of which the principle components are host auto-antigens and antibodies. The contribution of host lipids to the formation of these autoimmune complexes remains poorly defined. The aim of the present study was to identify and analyze candidate lipid autoantigens and their corresponding anti-lipid antibody responses in a well-defined SLE patient cohort using a combination of immunological and biophysical techniques. Disease monitoring in the SLE cohort was undertaken with serial British Isles Lupus Assessment Group (BILAG) scoring. Correlations between specific lipid/anti-lipid responses were investigated as disease activity developed from active flares to quiescent during a follow up period. We report a significant negative correlation between anti-lipid antibodies for 24S-hydroxycholesterol, cardiolipin and phosphatidylserine with SLE disease activity. Taken together, these data suggest that lipid autoantigens represent a new family of biomarkers that can be employed to monitor disease activity plus the efficacy of therapeutic intervention in SLE

Synthesis of europium-doped fluorapatite as a promising luminescent biomaterial

Lanthanide-doped apatite biomaterials are highly promising in medicine because of their excellent chemical and optical properties. In this study, Eu(III)-doped fluorapatite particles have been successfully synthesized by a wet method at room temperature. The characterization study from XRD showed that obtained powder is monophasic fluorapatite. Biomaterials based on fluorapatite (Ca10(PO4)5F2) doped with lanthanide elements are ideal contrast agents for a variety of biomedical applications, e.g. detection, imaging, cell tracking, and therapy [1]. Eu(III) received a great deal of interest because of several desirable properties like emission in the visible region, long luminescent lifetime, and less sensitivity to quenching by singlet oxygen [2].IX International School and Conference on Photonics : PHOTONICA2023 : book of abstracts; August 28 - September 1, 2023; Belgrad

First study of electrochemical behavior of herbicide pethoxamid and its voltammetric determination in river water

Pethoxamid (POA) is relatively new herbicide and it belongs to group of chloroacetamides. It inhibits the germination of target weeds in corn, soybeans, peas and beans, tobacco and other crops and it can affects on herbicide-resistant weeds. There are no many research records about this, in the future quite applicable, herbicide. Bearing in mind that pethoxamid is high soluble in water, with almost no sorption in soils [1], the leaching and runoff of this compound in ground and surface water is a real threat. Pethoxamid residues in soil, water food and feed of plant origin usually were determined by using liquid chromatography with tandem mass spectrometry (LC–MS/MS) [2] while some other analytical methods were used for determination of pesticides [3]. The electroanalytical methods are noted as fast and cost-effective analytical methods for determination of many analytes of environmental interest. As far as we know, this is a first report about electrochemical behavior of herbicide pethoxamid and its electroanalytical determination. This method is based on the electrochemical oxidation of pethoxamid in Britton-Robinson buffer solution at pH 4 at a boron-doped diamond electrode. This type of carbon electrode is almost resistant to contamination of surface with various chemical spaces, easy to maintain and has a very wide working potential window which could provide insight into the electrochemical oxidation of pethoxamid at high anodic potentials. All electrochemical measurements (cyclic and square-wave voltammetry) were performed on PalmSens 3 potentiostat/galvanostat/impedance analyzer with PSTrace software (PalmSens BV, Netherlands). Three-electrode system in the electrochemical cell was consisted from Ag/AgCl (1M KCl) reference electrode and platinum wire counter electrode, while working electrode was boron-doped diamond electrode. BDD electrode was electrochemicaly prepared as it was written before [4]. Cyclic voltammetry provided a well defined oxidation peak at +1.35 V, and this peak was used as a peak of quantification at a optimal pH value 4 (Figure 1 a). The square-wave voltammetry was chosen as suitable technique for analytical determination of pethoxamid with an established optimal working conditions (pulse amplitude of 60 mV and frequency of 10 Hz). The voltammograms obtained for standard solutions from 1 to 100 μM and corresponding calibration curve were shown on Figure 1 b. The method was applied for selective quantification of pethoxamid from spiked river water samples with good recovery of 92.0 to 104.6% for standard solutions of POA and good agreement with comparative HPLC method (97.6-98.1%). The results of this research indicate successful, fast, simple, reliable and cheap estimation of pethoxamid content in the surface water samples with no electrode surface modification and time-consuming sample preparation

Levels of oxysterol and anti-oxysterol IgG in SLE patients’ plasma.

<p>Analysis by GC<i>-</i>MS and ELISA show higher levels of oxidized cholesterols or anti-cholesterol IgGs in patients during flare versus follow-up period. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0055639#pone-0055639-g002" target="_blank">Figure 2ai and 2 aii</a>. 7-α-hydroxycholesterol levels and anti-7-α-hydroxycholesterol IgG levels in plasma. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0055639#pone-0055639-g002" target="_blank">Figure 2bi and 2bii</a>. 7-β-hydroxycholesterol levels and anti-7-β-hydroxycholesterol IgG levels in plasma. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0055639#pone-0055639-g002" target="_blank">Figure 2ci and 2cii</a>. 7-ketocholesterol levels and anti-7-ketocholesterol IgG levels in plasma. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0055639#pone-0055639-g002" target="_blank">Figure 2di and 2dii</a>. 24S-hydroxycholesterol levels and anti-24S-hydroxycholesterol IgG levels in plasma. p<0.05 value was considered as significant in Wilcoxon test.</p

Levels of unsaturated fatty acids and anti-unsaturated fatty acids IgG in SLE patients’ plasma.

<p><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0055639#pone-0055639-g003" target="_blank">Figure 3ai and 3ai</a>i. Phosphatidylserine levels and anti-phosphatidylserine IgG levels in plasma. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0055639#pone-0055639-g003" target="_blank">Figure 3bi and 3bii</a>. Isoprostane (15-F_2t-IsoP +5-F_2t-IsoP) levels normalized against AA values and anti-15-F_2t-IsoP IgG levels in plasma. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0055639#pone-0055639-g003" target="_blank">Figure 3ci</a>. Isoprostane (8-F_2t-IsoP) levels normalized against AA values. p<0.05 value was considered as significant in Wilcoxon test.</p